The present invention relates to shock absorbers such as, for example, railroad pads mounted on fixed buffers or on trucks, cars or railroad engines, pads arranged vertically at the bottom of elevator shafts, or again certain harbor stops.
It relates particularly, among such shock absorbers to those including two mutually encircling stacks, of alternated metallic elements and elastic elements, adapted for one to bear against the other, with compression of the elastic elements, when shocks are received.
It is an object of the invention to confer on such shock absorbers good qualities of responsiveness and of flexibility for the damping of weak impacts and a high capacity for the storage of energy for the damping of severe impacts.
It is another object of the invention to render the manufacture and assembly of such dampers particularly simple.
According to the invention therefore there are provided shock absorbers of the kind concerned characterised essentially in that the elastic elements of each stack are held by metal elements of the other stack and in that the elastic elements of the two stacks are constituted respectively of elastomers having different characteristics of deformation and of damping.
In preferred embodiments, recourse is had to one and/or the other of the following features:
The elastic elements of one of the stacks have a damping ratio less than 10% and those of the other stack, a damping ratio higher than 10%,
The stack comprising the elastic elements with the higher damping ratio is outside the other stack,
A slight axial pre-stress is exerted on the elastic elements with the lower damping ratio,
The surfaces, of the elastic elements with the lower damping ratio, coming into contact with the metal elements inserted between them for the resting state of the shock absorber are narrow and convex,
Certain of the elastic elements are designed to work on buckling when they are compressed axially.
The invention comprises, apart from these main features, certain other features which are preferably used at the same time and which will be more explicitly considered below.
In the following, a preferred embodiment of the invention will be described with reference to the accompanying drawing given of course purely by way of non-limiting example.